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Radiation Protection Fundamentals

Radiation Protection Fundamentals. Craig Maxwell - RCT Radiation Protection Group Lawrence Berkeley National Laboratory. Objectives. Familiarize you with some of the basics of Radiation and Radioactive Decay Discuss some of the common instruments found in research labs

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Radiation Protection Fundamentals

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  1. Radiation Protection Fundamentals Craig Maxwell - RCT Radiation Protection Group Lawrence Berkeley National Laboratory

  2. Objectives • Familiarize you with some of the basics of Radiation and Radioactive Decay • Discuss some of the common instruments found in research labs • Review control methods used to reduce exposure

  3. Nucleus Neutrons + + + Protons Electrons (Electron Clouds) Structure of the Atom

  4. Ionizing radiation • High energy radiation • Gamma-rays, x-rays - photons • Particles: alpha, beta, neutron • Ejects electrons from atoms • Produces an altered atom - an ion • Non-ionizing radiation • Low energy • Lasers, RF, microwaves, IR, visible • Excites electrons • Produces heat

  5. Alpha Decay Your skin will stop it 4He Nucleus Ejected from Nucleus internal hazard stopped by paper found in soil, radon and other radioactive materials

  6. Beta Decay Either too many neutrons or too many protons skin, eye and internal hazard stopped by plastic Naturally occurring in food, air and water

  7. Gamma / X-ray Decay • Emission of a photon • Often occurs after  or  when nucleus is in an excited state stopped by lead naturally present in soil and cosmic radiation medical uses

  8. Types of Ionizing Radiation Paper Plastic Lead Concrete Alpha Helium nucleus (2 protons, 2 neutrons): +2 charge Beta Electron: +1 or -1 charge Gamma and X-rays Photon: 0 charge Neutron Neutron: 0 charge

  9. Radiation Absorbed Dose Qty: Dose Unit: rad (Gray) 1 rad - 1000 mrad 1 rad = 100 erg/gram 1 Gy=100 rad Radioactivity Qty: Activity Unit: Curie (Bequerel) 1 Ci = 1000 mCi 1 Bq = 1 dis per sec 1 Ci = 3.7 e10 Bq roentgen equivalent man Radiation Risk Qty: Dose Equivalent Unit: rem (Sievert) 1 rem = 1000 mrem 1 Sv=100 rem Radiation Quantities and Units

  10. Radiation Weighting Factors (WR) Absorbed dose (Rad/Gy) x WR = Equivalent dose (rem) 10CFR835

  11. Sources of Ionizing Radiation • Radioactive materials • Naturally occurring (uranium, carbon-14, …) • Artificial (activated by neutrons from a reactor or accelerator beam) • Radiation Producing Machines • X-ray machines (characteristic, bremstrahlung) • Accelerators (ion beams, neutrons, x-rays)

  12. Background and Manufactured Radiation In the U.S. Contributes 360 mrem per year

  13. Manufactured Sources of Radiation Cigarette Smoking - 1300 mrem Medical – 53 mrem Medical Doses: A: Dental exam (16 mrem) B: Mammogram (25 mrem) C: Tc-99m cardiac function (75 mrem) D: Cranial CT multiple scans (up to 5 rem) E: “Full body CT screening” – one scan ( 1 to 2 rem) F: Spiral whole body CT scan ( 3 to 10 rem) Building Materials - 3.6 mrem Smoke Detectors - 0.0001 mrem mrem Fallout < 1

  14. Whole Body Annual Dose Limits RADIATION WORKER - Federal NRC Limits Whole Body - 5000 mrem/year Extremities - 50,000 mrem/year Skin - 50,000 mrem/year Eyes - 15000 mrem/year Pregnant - 500 mrem/term / 50 mrem/month General Pubic - 100 mrem/year

  15. Effect of Dose and Dose Rate 5 min 100 rems Localized effects: >500 REM Skin – radiation burn 20 years Whole body effects: LD50/30 500 RAD Chronic exposures may increase cancer risk. 100,000 people exposed to 100 mREM 4 or 5 additional cancers

  16. Risk Perspective Average Estimated Days Lost Due to Daily Activities Health RiskAve. Est. Days Lost Unmarried Male 3,500 Cigarette Smoking 2,250 Unmarried Female 1,600 Coal Miner 1,100 25% Overweight 777 Alcohol (U.S. average) 365 Construction Worker 227 Driving a Motor Vehicle 207 100 mrem/year for 70 years 10

  17. Radiation vs Contamination

  18. Radiation Vs. Radioactive Contamination Radiationis particles or waves of energy emitted from unstable atoms. Radioactive Contaminationis radioactive material usually in any location you do not want it. Exposing a material to radiation does not necessarily make it radioactive, but radioactive material on a non-radioactive item, makes the item contaminated.

  19. Radiation Survey Meters Two common Ion Chamber radiation survey instruments are: Victoreen Bicron

  20. Beta Contamination Instrument Ludlum 3 Type: Normally equipped with a Geiger-Mueller 44-9 (pancake) probe Detects: Beta, gamma

  21. Alpha/Beta Contamination Instrument Ludlum 2224 Type: Plastic scintillation for beta detection that has a [ZnS (Ag)] coating for alpha detection Detects: Alpha and Beta

  22. Other Instrumentation Ludlum 16 with a 44-3 thin window NaI probe Liquid Scintillation (LSC)

  23. Instrument performance • Dead or low batteries - erratic or no detection • Calibration has changed - may read high or low • Defective cable or other problems • Poor survey technique • angle of probe to source - only detects part • to far from source - radiation absorbed by air • survey too fast – only detects part You must use them correctly if you expect them to work for you

  24. Radiation & Contamination Control Methods Used to reduce exposure to radiation and radioactive material contamination

  25. Engineering Controls • Containment • Glove box • Glove bag • Ventilation • Fume Hood • Bio Safety Cabinet

  26. Engineering Controls cont. • Interlocks • Tamper-Proof Screws/Bolts • Flange Padlocks • Security Seals • Shielding • Access controls (e.g. card key)

  27. Administrative Controls • Regulations • Formal Authorizations • Facility policies and procedures • Labels, signs, and postings • Routine radiation surveys • Machine operational restrictions

  28. ALARA As Low As Reasonably Achievable Reduce Radiation Doses ALARA Techniques: • Time - (Reduce) • Distance – (Increase) • Shielding – (Proper Shielding)

  29. Control Methods • Engineering • Administrative • ALARA Techniques • Time • Distance • Shielding • Missing Control

  30. Exposure Prevention Methods • Protective clothing such as lab coats, gloves & safety glasses • Self-monitoring to reduce the spread of radioactive contamination

  31. Good Work Practices Use deliberate movements and apply lessons learned from cold runs (mock-ups).

  32. Respect and Understand the Postings Treat all radiological areas as if everything was contaminated.

  33. Common sources of radioactive contamination • Sloppy work practices • Poor housekeeping • Opening radioactive materials/systems without proper controls • Leak or tears in containers • Damaged Sealed Sources • Spills

  34. Upon Completion of Work Be sure to survey yourself

  35. Upon Completion of Work Hand washing is a good work practice and an important final step after working with any radioactive material.

  36. Final Thoughts • It is our mission to ensure that research and learning continue in the safest manner possible. • Be a mentor • Be a resource • Lead by example • Always use best practices

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